| First Author | Pérez-Liébana I | Year | 2022 |
| Journal | J Neurosci | Volume | 42 |
| Issue | 19 | Pages | 3879-3895 |
| PubMed ID | 35387872 | Mgi Jnum | J:352469 |
| Mgi Id | MGI:7706120 | Doi | 10.1523/JNEUROSCI.1463-21.2022 |
| Citation | Perez-Liebana I, et al. (2022) A Ca(2+)-Dependent Mechanism Boosting Glycolysis and OXPHOS by Activating Aralar-Malate-Aspartate Shuttle, upon Neuronal Stimulation. J Neurosci 42(19):3879-3895 |
| abstractText | Calcium is an important second messenger regulating a bioenergetic response to the workloads triggered by neuronal activation. In embryonic mouse cortical neurons using glucose as only fuel, activation by NMDA elicits a strong workload (ATP demand)-dependent on Na(+) and Ca(2+) entry, and stimulates glucose uptake, glycolysis, pyruvate and lactate production, and oxidative phosphorylation (OXPHOS) in a Ca(2+)-dependent way. We find that Ca(2+) upregulation of glycolysis, pyruvate levels, and respiration, but not glucose uptake, all depend on Aralar/AGC1/Slc25a12, the mitochondrial aspartate-glutamate carrier, component of the malate-aspartate shuttle (MAS). MAS activation increases glycolysis, pyruvate production, and respiration, a process inhibited in the presence of BAPTA-AM, suggesting that the Ca(2+) binding motifs in Aralar may be involved in the activation. Mitochondrial calcium uniporter (MCU) silencing had no effect, indicating that none of these processes required MCU-dependent mitochondrial Ca(2+) uptake. The neuronal respiratory response to carbachol was also dependent on Aralar, but not on MCU. We find that mouse cortical neurons are endowed with a constitutive ER-to-mitochondria Ca(2+) flow maintaining basal cell bioenergetics in which ryanodine receptors, RyR2, rather than InsP(3)R, are responsible for Ca(2+) release, and in which MCU does not participate. The results reveal that, in neurons using glucose, MCU does not participate in OXPHOS regulation under basal or stimulated conditions, while Aralar-MAS appears as the major Ca(2+)-dependent pathway tuning simultaneously glycolysis and OXPHOS to neuronal activation.SIGNIFICANCE STATEMENT Neuronal activation increases cell workload to restore ion gradients altered by activation. Ca(2+) is involved in matching increased workload with ATP production, but the mechanisms are still unknown. We find that glycolysis, pyruvate production, and neuronal respiration are stimulated on neuronal activation in a Ca(2+)-dependent way, independently of effects of Ca(2+) as workload inducer. Mitochondrial calcium uniporter (MCU) does not play a relevant role in Ca(2+) stimulated pyruvate production and oxygen consumption as both are unchanged in MCU silenced neurons. However, Ca(2+) stimulation is blunt in the absence of Aralar, a Ca(2+)-binding mitochondrial carrier component of Malate-Aspartate Shuttle (MAS). The results suggest that Ca(2+)-regulated Aralar-MAS activation upregulates glycolysis and pyruvate production, which fuels mitochondrial respiration, through regulation of cytosolic NAD(+)/NADH ratio. |
